The present invention relates to a new and improved apparatus for producing surfaces at the blade head of a cutter blade formed of hardened steel for use in the cutter head of a gear cutting machine.
A steel cutter blade, suitable for use in a cutter head of a gear cutting machine, originally has a rod or bar-shaped configuration i.e. bar stock, with four-cornered cross-sectional shape. This steel cutter blade, prior to mounting at the cutter head, must be provided at one end thereof with a cutter blade head portion. The cutter blade head portion or blade head is formed by a number of surfaces which are more or less inclined with respect to the lengthwise axis of the steel cutter blade, and between two of these surfaces there is formed the actual cutting edge at a common edge or corner thereof.
To produce the surfaces of the cutter blade heads of the individual blades of a cutter head it is conventional practice to insert a number of steel cutter blades into a machine, typically of the type disclosed, for instance, in Swiss Pat. No. 450,949. In such machine the same surfaces of the cutter blade head of the individual cutters or blades are simultaneously ground. This is accomplished such that the grinding disk is incrementally advanced towards the blades by fractions of a millimeter. Hence, the part of the steel cutter blade which is to be removed is ground away in layers, until there is exposed the desired surface of the cutter blade heads.
With this technique of forming the surfaces of the cutter blade head, it is necessary to usually remove a large number of layers of the material of the steel cutter blade. This requires an appreciable expenditure in both time and work. Hence, it is hardly possible to accelerate the grinding operation by only removing or machining away a few, but correspondingly thicker layers of material. It is to be appreciated that during grinding the output which is to be expended by the grinding machine is partially converted into heat at the surfaces of the steel cutter blade which are to be ground. The thickness of the layers which are to be machined thus should be chosen such that not too great amount of heat is delivered to the steel cutter blades, and between two successive passes of the grinding disk the last ground surface must be able to satisfactorily cool. If this is not so, then structural changes can arise at the surfaces of the steel cutter blade which are to be formed, and there are undesirably altered the properties of the steel cutter blade.